Gaia 20eae: A Newly Discovered Episodically Accreting Young Star

Abstract

The Gaia Alert System issued an alert on 2020 August 28, on Gaia 20eae when its light curve showed a ∼4.25 magnitude outburst. We present multiwavelength photometric and spectroscopic follow-up observations of this source since 2020 August and identify it as the newest member of the FUor/EXor family of sources. We find that the present brightening of Gaia 20eae is not due to the dust-clearing event but due to an intrinsic change in the spectral energy distribution. The light curve of Gaia 20eae shows a transition stage during which most of its brightness (∼3.4 mag) has occurred on a short timescale of 34 days with a rise rate of 3 mag/month. Gaia 20eae has now started to decay at a rate of 0.3 mag/month. We have detected a strong P Cygni profile in Hα, which indicates the presence of winds originating from regions close to the accretion. We find signatures of very strong and turbulent outflow and accretion in Gaia 20eae during this outburst phase. We have also detected a redshifted absorption component in all of the Ca ii IR triplet lines consistent with a signature of hot infalling gas in the magnetospheric accretion funnel. This enables us to constrain the viewing angle with respect to the accretion funnel. Our investigation of Gaia 20eae points toward magnetospheric accretion being the phenomenon for the current outburst.

Photometric and Spectroscopic Study of the EXor-like Eruptive Young Star Gaia19fct

“…The amplitude of 2019 brightening is higher than 4.8 mag, the largest burst in Gaia19fct, and is categorized as an outburst (ΔV = ∼ 2.5−6 mag; Fischer et al 2022). The high amplitude is similar to what is typical for FUors (Fischer et al 2022, and references therein), as well as the most powerful outbursts found in EXors (EX Lup, Ábrahám et al 2019;Rigliaco et al 2020;Gaia20eae, Cruz-Sáenz de Miera et al 2022a;Ghosh et al 2022). The peak brightness was reached in 2019 December within ∼70 days since the beginning of the outburst (2019 October), resulting in a steep rising rate of −0.072 mag day −1 .…”

“…Detection of time-coherent small-scale variability can be used to constrain the inner disk dynamic or at least the outer environment in FUors and EXors. The bestestablished results are usually obtained when the light curves are continuously gathered by a spacecraft (Siwak et al 2013(Siwak et al , 2018(Siwak et al , 2020Hodapp et al 2019;Szabó et al 2021), but this kind of analysis is also possible for well-sampled ground-based light curves (Green et al 2013;Baek et al 2015;Hackstein et al 2015;Ghosh et al 2022).…”

“…Thanks to the whole-sky monitoring of the Gaia space mission and its Gaia Photometric Science Alerts Program 12 (Hodgkin et al 2021), which announces targets that show an abrupt brightening or fading, the number of eruptive young stars has been increasing. These discoveries have been classified as FUors (Gaia17bpi, Hillenbrand et al 2018;Gaia18dvy, Szegedi-Elek et al 2020), EXors (Gaia18dvz, Hodapp et al 2019;Gaia20eae, Cruz-Sáenz de Miera et al 2022a;Ghosh et al 2022), andin between (Gaia19ajj, Hillenbrand et al 2019;Gaia19bey, Hodapp et al 2020).…”

TANSPEC: TIFR-ARIES Near Infrared Spectrometer

“…As the target region was crowded, we have carried out the PSF photometry to get the magnitudes of the stars. The obtained color correction equations for NIR filters (JHK s ) of the TANSPEC on the 3.6-m DOT for calibrating to Two Micron All Sky Survey (2MASS) magnitudes are as follows (see also, [7]).…”

“…(i P 1 − i) = (−0.01 ± 0.01) × (r P 1 − i P 1 ) − 6.05 ± 0.02 (7) where, r P 1 and i P 1 denote the standard magnitudes of the stars taken from the PS1 data release 1 catalog § § §, and r and i are the present instrumental magnitudes of the similar stars normalized per sec exposure time.…”